Ovariectomy is a term used for ovarian removal. It could be unilateral (partial) or bilateral (complete) when one ovary or both ovaries are removed respectively. The aims of various workers in the field differed. Bast and Greenwald (1977) observed that small follicles proliferate to large ones after unilateral ovariectomy (ULO). Howland and Skimer (1973) observed that FSH levels are increased only during a short period of 24 hours after ULO and not during later days. Also Welshen and Dullaart (1974) in the rat, Best and Greenwald (1977) in the hamster showed that FSH levels are increased from 4 hours after ULO.

On the estrogen level after ULO, Baranczuk and Greenwald (1973) found increase and unchanged plasma estradial levels in hamsters at 7 and 31 hours respectively after ULO, and estradial levels in the rat after ULO at diestrus appeared not to decrease in comparism to those in control rats, while progesterone is lower between 4 and 20 hours after ULO. De Jong et al (1978) observed minor changes in circulating estradial level after bilateral ovariectomy (BLO) on the days of proestrus and metestrus.

Battey and Romeo (1951) evolved ovariectomy as a remedy of otherwise incurable ovarian diseases. Apart from the aims expressed above by the above workers other aims include (1) to study the ovarian functions as they relate to the reproductive ages. (2) Determine the ovulation rate in the remaining intact ovary. (3) Determine the mechanism of ovarian hypertrophy (4) To determine whether litter sizes are affected by removing one ovary. (5) Evaluate the effects of performing the ovariectomy at particular stage of the cycle and measuring serial hormonal levels immediately after ovariectomy and a high period up to 31 hours. (6) Measurement of gonadotrophins and plasma steroid hormones. (7) Inducing menopause and monitoring the extra-ovarian sex hormonal levels and gonadotrophin levels. The aims generally varied. The present study was aimed at evaluating the levels of sex hormones (testosterone progesterone, and estrogen) and to determine whether it is necessary to prolong the study time beyond 48 hours as practiced by many workers as the period of study (48 hours or less) might be affected by stresses due to surgery and anaesthesia including environmental factors.

Materials and Methods:

Twenty-eight adult albino rats of Wistar strain were used. Their weights ranged from 115-120gms, aged between 5 weeks to 6 weeks. Guinea pellets feeds were used throughout the experiment. The rats were distributed in 3 cages of 10, 10, 8 before the operation. Surgical instruments were sterilized in autoclave. Silk and chronic suture materials were used. Tap water was provided ad libitum throughout  the period. After surgery, the rats were housed in group of 4 and 5 in a cage. Three weeks post operation; they were returned to their pre-operational groupings before they were scarified. Room temperature was 26-28^OC. The mean weights at sacrifice were noted (control – 155 ± 2.7, unilateral = 162.6 ± 1.8 and bilateral = 172.5 ± 2.6g).

Method

A single longitudinal skin incision was made on the dorso-lateral area at the level of the lower poles of the kidney after shaving the furs with scissors and cleansing with 70% alcohol. The skin was retracted laterally toward one side and the ovary exposed through a thin muscle mass just below the dorsal muscle mass. Each incision was of minimum length to allow the extrusion of ovary. Ligation of the upper horn of the uterus, including the arteries with chromic catgut was carried out. Ovary was excised and wounds were closed. High degree of aseptic procedure was maintained throughout the operation. Operations were carried out in estrus phases as determined by vaginal smears using Shorr’s stain. Light ether anaethesia was used to put the animal to sleep. After recovery, the animals were put 4-5 rats per cage for a period of three weeks  thereafter were put 8-10 rats in a cage as in pre-operational stage. Markers were used to distinguish them. They were sacrificed while in estrus by decapitation at 6 weeks and the blood samples collected. The sera were collected after being centrifuged and stored at 10^OC and later assayed for various hormones using Radio Immuno Assay technique. Results obtained were compared with the result obtained from other workers less 48 hours following ovariectomy.

Vaginal Cytology:

The vaginal smears from the groups were studied (fig, 1a, b & c). First under low power (x10) to access the cell yield and finally under high power (x40) with microscope. The smears of the group 1 and group 2 were similar in pictorial outlook with the background showing many cornified, non-nucleated epithelial cells without leucocytes indicating estrus phase. Group 3 failed to show estrus picture rather showed many leucocytes with nucleated epithelial cells indicating diestrus phase.

(Figure 2)

Discussion

Various workers – Baranczuk, Welschen and Dullaart (1974), Bast and Greenwald 1977, De Jong et al 1978 and others estimated the levels of steroid hormones before 48 hours of surgery but our study was extended to six weeks with hope that this period was long enough to allow the effects of stress induced surgery and anaesthesia including other environmental factors that could interfere with the result to wane. The results were then compared with their own.

Barancz and Greenwald (1973) found an increase and unchanged plasma estradiol levels in hamster at 7 and 31 hours respectively after ULO in the rat.  Estradiol levels at diestrus was not significantly decreased when compared with the control. Progesterone level was found to be lower between 4 to 20 hours after ULO. Mandl (1951) observed that ovariectomy, irrespective of the time of hormonal estimation caused significant increase in the levels of testosterone and decrease in progesterone and estradiol levels. Also Noble (1939) showed that in complete ovariectomised rats, the high testosterone observed maintained the female rats in diestrus phase.

The result of the present study showed that testosterone level was significantly elevated in group 3 as demonstrated by Noble (1939). Vaginal cytology also showed that the smears taken from this group showed persistent diestrus phase as was also observed by Noble (1939).

Progesterone and estradiol levels were significantly decreased in group 3.  The decrease in group 2 was not significant when compared with control group. This agreed with the work of Mandl (1951) who found significant decrease in progresterone and estradiol.  This work does not therefore propose a longer period of sex hormone estimation following ovariactomy as results obtained six weeks post ovariectomy did not differ significantly from the ones obtained before 48 hours by Mandl (1951) Noble (1939) and Greenwald et al (1977).

It is concluded therefore that surgical and anesthetic stresses have no effect on ovariectomy irrespective of the time of sex hormonal estimation as sex hormone values obtained before 48 hours and 6 weeks post normal ovariectomy did not differ significantly.